Exercise Reverses Disuse Atrophy In Rat Gastrocnemius Muscle

Abstract

PURPOSE: To investigate the effects of different exercise interventions on disuse atrophy and atrophy-related proteins in rat gastrocnemius muscle. METHODS: Male Sprague-Dawley rats were randomly divided into a control group (C, n=16) and a suspension group (T, n=40). Rats in the T group were suspended by a tail suspension system for two weeks. Rats in the C group were further divided into a post-suspension blank group (C1) and a post-exercise blank group (C2), and rats in the T group were further divided into a post-suspension control group (T1), a post-exercise control group (T2), an endurance exercise group (TA), a resistance exercise group (TR) and a combined endurance and resistance exercise group (TAR). Rats in the TA, TR, and TAR groups were subjected to exercise training for four weeks. Body weight and wet weight of gastrocnemius muscle were measured immediately after suspension or at 24 hours after the last training session. Protein expression levels of Muscle Ring Finger 1 (MURF1), Muscle Atrophy F-Box (MAFbx), Insulin-Like Growth Factor-1 (IGF-1) and Cysteinyl Aspartate Specific Protease-3 (Caspase-3) in gastrocnemius muscle were determined by western blot. Student t-tests and one-way ANOVAs were used for data analysis. RESULTS: After suspension, body weight and wet weight of gastrocnemius muscle in the T1 group were significantly lower than those in the C1 group (p<0.05 to p<0.01). After exercise intervention, body weight, wet weight of gastrocnemius muscle, and the protein expression levels of MAFbx in the TA, TR, and TAR groups were significantly higher than those in the T2 and C2 groups, the protein expression levels of Caspase-3 in the TA, TR and TAR groups were significantly lower than those in the T2 and C2 groups, and the protein expression levels of MuRF1 in the TA and TR groups were significantly lower than those in the T2 group (p<0.05 to p<0.01). CONCLUSIONS: Exercise interventions, such as endurance exercise, resistance exercise, and combined endurance and resistance exercise, can effectively reverse disuse atrophy of gastrocnemius muscle in rats, which may be through altering the expression levels of several atrophy-related proteins.